In motorized fans, a motor drives a hub which supports a multiplicity of radially extending fan blades. The positions of the supports are subject to great stress. Moreover, the blades to the hub may be subject to vibrations or other stresses that damage the blades or the hub. These and other factors make it necessary to remove blades from their supports on the hub and to attach new blades at these supports. To avoid the necessity of removing all the blades when only one or some are damaged, it is desirable to be able to remove one at a time. However, singly removable blades are difficult to secure, particularly in view of stresses endured by the blades, and the tendency of objects subject to vibration to loosen.